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	$197.33	10.625%	$218.2963	$218.30	$218.30	$218.30
Purchase #2	$182.74	10.711%	$202.3133	$202.31	$202.30	$202.30
Purchase #3	$6.59	12.283%	$7.3994	$7.40	$7.40	$7.40
Purchase #4	$179.64	9.264%	$196.2818	$196.28	$196.30	$196.30
Purchase #5	$228.62	8.681%	$248.4665	$248.47	$248.45	$248.50
Purchase #6	$42.63	7.364%	$45.7693	$45.77	$45.75	$45.80
Purchase #7	$84.45	7.560%	$90.8344	$90.83	$90.85	$90.80
7 purchase totals =	$922.00		$1,009.3610	$1,009.36	$1,009.35	$1,009.40