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	$103.65	7.185%	$111.0973	$111.10	$111.10	$111.10
Purchase #2	$12.47	12.871%	$14.075	$14.08	$14.10	$14.10
Purchase #3	$167.87	8.360%	$181.9039	$181.90	$181.90	$181.90
Purchase #4	$162.76	4.471%	$170.037	$170.04	$170.05	$170.00
Purchase #5	$152.32	9.688%	$167.0768	$167.08	$167.10	$167.10
Purchase #6	$6.28	11.820%	$7.0223	$7.02	$7.00	$7.00
Purchase #7	$88.50	7.650%	$95.2703	$95.27	$95.25	$95.30
7 purchase totals =	$693.85		$746.4826	$746.49	$746.50	$746.50