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	$159.42	6.417%	$169.65	$169.65	$169.65	$169.70
Purchase #2	$68.31	4.326%	$71.2651	$71.27	$71.25	$71.30
Purchase #3	$198.98	4.545%	$208.0236	$208.02	$208.00	$208.00
Purchase #4	$209.50	11.449%	$233.4857	$233.49	$233.50	$233.50
Purchase #5	$158.96	11.192%	$176.7508	$176.75	$176.75	$176.80
Purchase #6	$165.54	13.123%	$187.2638	$187.26	$187.25	$187.30
Purchase #7	$88.46	11.109%	$98.287	$98.29	$98.30	$98.30
7 purchase totals =	$1,049.17		$1,144.7260	$1,144.73	$1,144.70	$1,144.90