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	$143.87	6.474%	$153.1841	$153.18	$153.20	$153.20
Purchase #2	$233.82	13.635%	$265.7014	$265.70	$265.70	$265.70
Purchase #3	$72.33	6.867%	$77.2969	$77.30	$77.30	$77.30
Purchase #4	$29.74	5.648%	$31.4197	$31.42	$31.40	$31.40
Purchase #5	$250.89	7.287%	$269.1724	$269.17	$269.15	$269.20
Purchase #6	$169.37	11.301%	$188.5105	$188.51	$188.50	$188.50
Purchase #7	$35.27	13.590%	$40.0632	$40.06	$40.05	$40.10
7 purchase totals =	$935.29		$1,025.3482	$1,025.34	$1,025.30	$1,025.40