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	$196.92	7.327%	$211.3483	$211.35	$211.35	$211.30
Purchase #2	$48.88	10.300%	$53.9146	$53.91	$53.90	$53.90
Purchase #3	$132.64	6.397%	$141.125	$141.13	$141.15	$141.10
Purchase #4	$182.47	7.155%	$195.5257	$195.53	$195.55	$195.50
Purchase #5	$50.89	9.845%	$55.9001	$55.90	$55.90	$55.90
Purchase #6	$159.46	7.703%	$171.7432	$171.74	$171.75	$171.70
Purchase #7	$57.79	5.674%	$61.069	$61.07	$61.05	$61.10
7 purchase totals =	$829.05		$890.6259	$890.63	$890.65	$890.50