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	$106.38	7.756%	$114.6308	$114.63	$114.65	$114.60
Purchase #2	$65.35	6.162%	$69.3769	$69.38	$69.40	$69.40
Purchase #3	$78.59	4.511%	$82.1352	$82.14	$82.15	$82.10
Purchase #4	$135.74	4.452%	$141.7831	$141.78	$141.80	$141.80
Purchase #5	$70.62	10.637%	$78.1318	$78.13	$78.15	$78.10
Purchase #6	$76.41	13.244%	$86.5297	$86.53	$86.55	$86.50
Purchase #7	$156.76	11.736%	$175.1574	$175.16	$175.15	$175.20
7 purchase totals =	$689.85		$747.7449	$747.75	$747.85	$747.70