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	$191.89	10.114%	$211.2978	$211.30	$211.30	$211.30
Purchase #2	$9.92	6.210%	$10.536	$10.54	$10.55	$10.50
Purchase #3	$249.64	9.229%	$272.6793	$272.68	$272.70	$272.70
Purchase #4	$178.72	13.251%	$202.4022	$202.40	$202.40	$202.40
Purchase #5	$81.98	9.517%	$89.782	$89.78	$89.80	$89.80
Purchase #6	$160.28	11.333%	$178.4445	$178.44	$178.45	$178.40
Purchase #7	$75.88	12.648%	$85.4773	$85.48	$85.50	$85.50
7 purchase totals =	$948.31		$1,050.6191	$1,050.62	$1,050.70	$1,050.60