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	$194.71	10.750%	$215.6413	$215.64	$215.65	$215.60
Purchase #2	$52.42	6.675%	$55.919	$55.92	$55.90	$55.90
Purchase #3	$233.98	12.873%	$264.1002	$264.10	$264.10	$264.10
Purchase #4	$57.38	9.443%	$62.7984	$62.80	$62.80	$62.80
Purchase #5	$226.48	7.515%	$243.5	$243.50	$243.50	$243.50
Purchase #6	$55.77	9.438%	$61.0336	$61.03	$61.05	$61.00
Purchase #7	$202.56	11.356%	$225.5627	$225.56	$225.55	$225.60
7 purchase totals =	$1,023.30		$1,128.5552	$1,128.55	$1,128.55	$1,128.50