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	$185.30	5.847%	$196.1345	$196.13	$196.15	$196.10
Purchase #2	$111.37	11.618%	$124.309	$124.31	$124.30	$124.30
Purchase #3	$181.89	10.652%	$201.2649	$201.26	$201.25	$201.30
Purchase #4	$159.38	5.357%	$167.918	$167.92	$167.90	$167.90
Purchase #5	$114.88	12.338%	$129.0539	$129.05	$129.05	$129.10
Purchase #6	$116.66	10.829%	$129.2931	$129.29	$129.30	$129.30
Purchase #7	$67.85	6.111%	$71.9963	$72.00	$72.00	$72.00
7 purchase totals =	$937.33		$1,019.9697	$1,019.96	$1,019.95	$1,020.00