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	$175.80	8.112%	$190.0609	$190.06	$190.05	$190.10
Purchase #2	$92.47	7.478%	$99.3849	$99.38	$99.40	$99.40
Purchase #3	$29.33	3.236%	$30.2791	$30.28	$30.30	$30.30
Purchase #4	$238.56	6.750%	$254.6628	$254.66	$254.65	$254.70
Purchase #5	$233.70	9.681%	$256.3245	$256.32	$256.30	$256.30
Purchase #6	$158.77	5.649%	$167.7389	$167.74	$167.75	$167.70
Purchase #7	$57.97	6.834%	$61.9317	$61.93	$61.95	$61.90
7 purchase totals =	$986.60		$1,060.3828	$1,060.37	$1,060.40	$1,060.40