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	$223.36	3.797%	$231.841	$231.84	$231.85	$231.80
Purchase #2	$88.47	3.460%	$91.5311	$91.53	$91.55	$91.50
Purchase #3	$160.27	4.764%	$167.9053	$167.91	$167.90	$167.90
Purchase #4	$243.63	7.146%	$261.0398	$261.04	$261.05	$261.00
Purchase #5	$137.46	6.138%	$145.8973	$145.90	$145.90	$145.90
Purchase #6	$96.59	9.114%	$105.3932	$105.39	$105.40	$105.40
Purchase #7	$81.70	11.765%	$91.312	$91.31	$91.30	$91.30
7 purchase totals =	$1,031.48		$1,094.9197	$1,094.92	$1,094.95	$1,094.80