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	$133.41	7.568%	$143.5065	$143.51	$143.50	$143.50
Purchase #2	$74.66	7.576%	$80.3162	$80.32	$80.30	$80.30
Purchase #3	$82.34	7.159%	$88.2347	$88.23	$88.25	$88.20
Purchase #4	$177.28	5.865%	$187.6775	$187.68	$187.70	$187.70
Purchase #5	$225.69	3.556%	$233.7155	$233.72	$233.70	$233.70
Purchase #6	$198.54	8.449%	$215.3146	$215.31	$215.30	$215.30
Purchase #7	$142.27	10.163%	$156.7289	$156.73	$156.75	$156.70
7 purchase totals =	$1,034.19		$1,105.4939	$1,105.50	$1,105.50	$1,105.40