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	$118.40	7.489%	$127.267	$127.27	$127.25	$127.30
Purchase #2	$170.38	5.153%	$179.1597	$179.16	$179.15	$179.20
Purchase #3	$232.69	8.841%	$253.2621	$253.26	$253.25	$253.30
Purchase #4	$203.44	6.318%	$216.2933	$216.29	$216.30	$216.30
Purchase #5	$60.78	5.582%	$64.1727	$64.17	$64.15	$64.20
Purchase #6	$89.53	11.226%	$99.5806	$99.58	$99.60	$99.60
Purchase #7	$209.35	4.147%	$218.0317	$218.03	$218.05	$218.00
7 purchase totals =	$1,084.57		$1,157.7671	$1,157.76	$1,157.75	$1,157.90