Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$219.41	11.206%	$243.9971	$244.00	$244.00	$244.00
Purchase #2	$152.66	9.654%	$167.3978	$167.40	$167.40	$167.40
Purchase #3	$157.27	9.472%	$172.1666	$172.17	$172.15	$172.20
Purchase #4	$166.36	7.826%	$179.3793	$179.38	$179.40	$179.40
Purchase #5	$189.85	9.689%	$208.2446	$208.24	$208.25	$208.20
Purchase #6	$142.74	13.870%	$162.538	$162.54	$162.55	$162.50
Purchase #7	$245.25	9.502%	$268.5537	$268.55	$268.55	$268.60
7 purchase totals =	$1,273.54		$1,402.2771	$1,402.28	$1,402.30	$1,402.30