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	$114.77	13.595%	$130.373	$130.37	$130.35	$130.40
Purchase #2	$245.67	7.183%	$263.3165	$263.32	$263.30	$263.30
Purchase #3	$199.74	4.329%	$208.3867	$208.39	$208.40	$208.40
Purchase #4	$69.46	12.402%	$78.0744	$78.07	$78.05	$78.10
Purchase #5	$160.26	3.214%	$165.4108	$165.41	$165.40	$165.40
Purchase #6	$118.38	13.577%	$134.4525	$134.45	$134.45	$134.50
Purchase #7	$196.45	5.312%	$206.8854	$206.89	$206.90	$206.90
7 purchase totals =	$1,104.73		$1,186.8993	$1,186.90	$1,186.85	$1,187.00